The continuing objectives of this amended grant are to promote and augment the development of a basic cancer research center devoted to collaborative, innovative investigation at a fundamental level with an eye to future clinical cancer research endeavors. Scientists from different backgrounds and different academic departments are coordinating their on-going research efforts to mount a frontal attack on the various aspects of cancer research. Efforts will be concentrated in five research programs, each under the direction of a senior scientist, as follows: Program 1: Cellular Functions and Growth Control: Intracellular Mechanisms; Program 2; Cell structure, Growth and Regulation; Program 3: Control of Hematopoietic Cell Differentiation and Proliferation; Program 4: Growth and Differentiation of Mammalian Endocrine Cells; Program 5: Antigen Recognition and Cellular Activation in Immune Responses. Most of the scientists in each of these five programs have had longstanding collaborative research programs. It is our intention to expand these efforts of existing staff investigators and to recruit new investigators who can bring fresh ideas and new techniques into these collaborative research efforts. The Cancer Research Center will provide the environment for interplay among staff investigators of all five programs, who will be using advanced central research facilities. The NCI Cancer Centers staff has justifiably ruled that we are a Basic Cancer Research Center, but with their encouragement, we shall continue independent development of clinical cancer research initiatives promoted entirely by local funds. Accomplishments during the first three years of CCSG support include: increase in Staff Investigators from 60 to 80; recruitment of seven New Investigators; doubling use by Staff Investigators of Shared Core Research Facilities; renewal of one and acquisition of another program-project grant; acquisition and renovation of new Cancer Center laboratories; development of a new Program in Cancer Immunology; and major expansion of Cancer Center seminars and symposia for greater interaction among Staff Investigators.